LAKE TO FOREST OR PRAIRIE 



243 



that one lake as it fills shall first give rise to marsh, then to 

 swampy forest, later to the succession of oak and hickory forest, 

 and finally to the climax 

 forest, while another, 

 after the marsh condi- 

 tion, proceeds through 

 wet meadow to prairie. 

 Possibly differences in 

 depth of the original 

 lake undergoing filling 

 and consequent differ- 

 ences in the depth of 

 humus, differences in 

 drainage, in soil char- 

 acter, as well as other 

 factors, enter into the 

 production of unlike 

 end results. 



Once the differences 

 between prairie and 

 forest are established, 

 it is easy to see enough 

 contrasts in atmospheric and soil temperatures, in water content 

 of the soil, in relative percentage or saturation of the atmos- 

 phere, to account in part, perhaps 

 entirely, for the very different 

 plants and animals in the two 

 regions. The temperatures in the 

 soil and among the vegetation of 

 the forest are not subject to such 

 Figs. 347, 348: Fig. 347 (top).— extremes, either seasonal or di- 



Forked-tail katydid, Scudderia , ^i ... 



furcaia; Fig. 348 (bottom) .-Texas ^rnal, as on^ the prairie. The 

 katydid, S. texensis. temperature in the forest and in 



its soil is lower in summer and at midday than on the prairie. 

 The cool air protected in summer by the forest trees is a much 



Fig. 346. — American bittern, Botaurus lenti- 

 ginosus. 



